1. Field of the Disclosure
The disclosure relates to a method for calibrating a spectrometric sniffing leak detector for various tracing gases to be detected, said method comprising using a defined calibration gas that preferably escapes through a test leak.
2. Discussion of the Background Art
Sniffing leak detectors are used for detecting a tracing gas escaping from a container to be tested for leaks. A typical field of application of sniffing leak detectors are refrigerators and air conditioners where a coolant is contained in a circuit sealed against the surroundings. During the quality control the tightness of the coolant circuit is to be checked. A sniffing leak detector takes in ambient air which is fed to a gas detector for determining whether a tracing gas is contained in the air taken in. Mere identification of the presence of a tracing gas is normally not sufficient. Further, information on the quantity of the escaping tracing gas and/or the size of the detected leak are required.
Sniffing leak detectors comprise a gas separation system as a gas detector, said gas separation system analyzing the gas mixture taken in. The gas separation system normally is a mass spectrometer. However, an infrared gas detector may also be used. The gas separation system determines the components contained in the gas mixture according to the mass number and the respective amplitude. The mass number indicates the molecular mass of the gas. Many gases comprise a combination of several peaks with different amplitudes.
There is a need for using a leak detector for detecting various tracing gases. Here, each tracing gas requires a separate calibration to be carried out. In U.S. Pat. No. 6,263,724 a gas analyzer comprising autocalibration means is described. A container comprising a calibrated test leak is filled with a mixture of n gases having different masses. The partial leakage flow of each of said n gases of the gas mixture is known. The mass number of each of said gases is determined. With the aid of such a calibrating method a calibration is carried out only for selected gases. If the leak detector is afterwards to be used for other gases, a new calibration using said tracing gas as calibrating gas is required.